1. Field of the Invention
The present invention relates to a packing method of packing an article in which an article is packed by wrapping a band around the article, tightening the band, cutting the band and adhering the ends of the band to each other, and also a packing apparatus for packing an article.
2. Description of the Prior Art
So-called xe2x80x9cband-wrapping packing apparatusesxe2x80x9d are known, which wrap a band around an article, tighten the band, cut the band and adhere the ends of the band to each other. The band-wrapping packing apparatuses comprise, for example, a sealing device and a band-feeding device. The sealing device has a sealing motor. When the sealing motor is driven, the sealing device holds a band, cuts the band and adhere the ends of the band to each other. The band-feeding device has a band reel, a drive motor and a drive roller. The drive motor can rotate the drive roller in a forward direction and the reverse direction. When rotated in the forward direction, the drive roller feeds a band from a band reel. When rotated in the reverse direction, the drive roller draws back the band and tightens the band.
The method in which a packing apparatus of this type packing an article comprises the following five steps:
(1) Band-inserting step of wrapping a band around the article and inserting the distal end of the band into a band insertion port;
(2) Band-holding step of holding the end of the band, which has been inserted into the band insertion port;
(3) Band-tightening step of drawing the band back, thus tightening the band around the article with an appropriate force;
(4) Band-sealing step of cutting the band and adhering the ends of the band to each other; and
(5) Band-feeding step of feeding the band for a prescribed distance from the band reel.
Packing apparatuses are classified into two types. The first type is an automatic one. The second type is a semiautomatic one.
The automatic packing apparatus has an arch unit. The arch unit is located above the table supporting the article to be packed or at one side of the table.
In the automatic packing apparatus, a band is automatically fed from the band reel into the arch unit. In the arch unit, the distal end of the band is inserted into the band insertion port and is held fast. When a power switch on the automatic packing apparatus is turned on, the band-feeding step, band-inserting step and band-holding step are automatically carried out. Thus, when a start switch on the apparatus is turned on after an article has been placed on the table, the apparatus carries out the band-tightening step and band-sealing step, thus automatically packing the article. The apparatus then performs the band-feeding step, band-inserting step and band-holding step, in preparation for the next packing cycle. In the band-tightening step, the band is pulled back from the arch unit, wrapped around the article and tightened around the article.
By contrast, the semiautomatic packing apparatus has no arch unit. After feeding a band for a prescribed distance, the apparatus waits until the power switch is turned on. The operator puts an article on the table, wraps the band around the article and inserts the end of the band into the band insertion port. When the end of the band is inserted into the port, the power switch is automatically turned on. Then, the apparatus automatically carries out the band-holding step, band-tightening step and band-sealing step, one after another. The article is thereby packed. Then, the apparatus performs the band-feeding step, in preparation for the next packing cycle. In the semiautomatic packing apparatus, the band-inserting step is manually performed, whereas the band-holding step, band-tightening step, band-sealing step and band-feeding step are automatically carried out, one after another.
In the packing apparatus, either automatic or semiautomatic, all steps, except the band-inserting step, are effected under automatic control that is accomplished by the sealing motor, the drive motor, and the like.
In the packing apparatus of either type, the force adjustment dial is turned to adjust and set a desired force for tightening the band. The apparatus of either type stops tightening the band when a sensor detects that the force applied to the band reaches the desired value. The semiautomatic packing apparatus has a band-length dial, too. This dial may be turned to preset a distance for which to feed the band in the band-feeding step.
In the automatic packing apparatus, the packing sequence starts when the start switch is manually turned on. In the semiautomatic packing apparatus, the packing sequence starts when the start switch is automatically turned on after the end of a band is manually inserted into the band insertion port. In either type of the apparatuses, the packing sequence cannot be interrupted once it has started. In other words, once started, the packing sequence continues until it completes one cycle of operation.
The conventional packing apparatuses, in which the packing sequence cannot be interrupted once the start switch is turned on, are disadvantageous in the following respects:
(1) If the band is wrapped around the article and tightened at a wrong position on the article, the position cannot be easily corrected. Further, if the band tightened around the article extends obliquely, it can hardly be straightened as is desired.
(2) Protective plates can hardly be placed on the article at desired positions to prevent the band from being wrapped directly on the article. This is because the operator""s hands may be caught in the gap between any protective plate and the band. Once arranged on the article, the protective plates cannot be easily adjusted in position.
(3) If the force preset to tighten the band around the article is improper, it cannot be adjusted at all.
If the band wrapped around the article can hardly straightened, if the protective plates cannot be adjusted in position, or if the force of tightening the band cannot be adjusted, the band must be cut and the packing sequence must be repeated. This lowers the packing efficiency. Particularly in packing a cardboard box, the band must be cut and the packing sequence needs to be performed again since the band is tightened while the two straps at the open top remain standing and these straps may not be closed.
Japanese Patent Application KOKAI Publication No. 57-153817, for example, discloses a packing method in which the band-tightening step is divided into a preliminary tightening step and a final tightening step. A band is tightened with a smaller force in the preliminary tightening step than in the final tightening step. After the preliminary tightening step and before the final tightening step, the band can be corrected in position and orientation, and any protective plate used can be adjusted in position. The final tightening step can be carried out, for example, while pushing the two straps of a cardboard box to close the open top thereof. Thus, the cardboard can packed and closed at the same time. In this packing method, too, the band is tightened with a preset force that cannot be adjusted at all.
Japanese Patent Application KOKAI Publication No. 57-153817 discloses a packing apparatus, too. This apparatus needs to have a preliminary tightening roller and a final tightening roller, in addition to the drive roller, and a mechanism for moving one of the band-tightening rollers. The preliminary tightening roller remains in contact with the drive roller. The mechanism moves the final tightening roller between two positions. At the first position, the final tightening roller contacts the drive roller. At the second position, it does not contact the drive roller. Comprising three rollers, the packing apparatus is complicated in construction.
Japanese Patent Application KOKAI Publication No. 11-171124 discloses a packing method. In this method, the drive roller is driven at a high speed in the first half of the band-tightening step and at a low speed in the latter half of the band-tightening step. More precisely, the drive roller draws a band back at 6 m/sec in the first half of the step, wrapping the band around an article, and pulls the band at 0.2 m/sec in the latter half of the step, tightening the band wrapped around the article. In the packing method, the band is pulled and tightened at a low speed in the latter half of the band-tightening step. This gives the operator a time long enough to correct the position and orientation of the band and to adjust the positions of the protective plates placed between the article and the band. In the first half of the band-tightening step, the band is drawn back for only the time set by a timer. In the latter half of the band-tightening step, the band is pulled until a sensor detects that the tension on the band reaches a preset value. It is therefore impossible to adjust the tension on the band, i.e., the force that tightens the band. An apparatus that performs this packing method must have a timer and a tension sensor and is inevitably complicated in construction.
A first object of the present invention is to provide a packing method which enables the operator to adjust the position and orientation of a band wrapped around an article, the positions of protective plates placed between the article and the band, and the force tightening the band.
A second object of the invention is to provide a packing apparatus which makes it easy for the operator to adjust the position and orientation of a band wrapped around an article and the positions of protective plates placed between the article and the band, which enables the operator to adjust the force tightening the band, and which can be simple in construction.
To achieve the first object, there is provided a packing method in which the distal end of a band is held even after the band-holding step, a switch is manually operated to control the drive roller in the next step, i.e., band-tightening step, and the band-sealing step and band-feeding step are automatically performed, after a signal is generated, indicating that the band-tightening step has been completed.
To attain the second object, there is provided a packing apparatus that comprises a band-tightening switch and a tightening stop switch, in addition to a sealing device and a band-feeding device. The band-feeding device has a drive roller. The tightening stop switch is manually operated to control the rotation of the drive roller. The tightening stop switch generates a signal indicating that a band has been completely tightened around an article.